I don't think will be possible anymore a full scale war like the WW1/WW2. I hope !
Only some skirmish and regional wars between the "marionettes" in the eternal game of power.
Why ?
Because there is something called ATOMIC BOMBS.
Even an small atomic device (aka "tactical") if it is unleashed, severe consciences will be.
http://nuclearsecrecy.com/nukemap/The ancestors were more wise than us: they never "play" with the BIG words. These words where TABU. They never says for example directly TIGER, who is a savage beast, a death-bringer.
Today we can hear the words WAR, NUCLEAR, DEATH so many times per day and these become so common like PIE, CHIPS, SODA..
Actually these words where striped by their meaning allowing the people to become more careless.
"The sleep of reason produces monsters".
Francisco Goya http://en.wikipedia.org/wiki/Goya